1. Field of the Invention
The present invention relates to a protective module using electric current to protect objects against threats, especially from shaped charges.
2. Description of the Prior Art
Various protective mechanisms are already in use to protect objects, for example combat tanks, from shaped charges. One protective mechanism provides for using electric current to disturb shaped charge jets. A basic principle of this electric protective mechanism is coupling an electric current into the jet generated by the shaped charge with the aid of two electrode plates, which then results in disturbing the jet.
Shaped charge jets are generated with the detonation of an arrangement of highly explosive substances about a conic or hemispherical intermediate metal ply and are especially suited for penetrating armor. Such type shaped charge jets are distinguished by a unidirectional aimed material jet developing in the course of the detonation. At its tip, the shaped charge jet has velocities in the range from about 7 km/s to 10 km/s. If such a shaped charge jet encounters an obstacle, such as for example armor, due to the jet pressure occurring with the great jet velocity, the material of the armor behaves in the magnitude of several hundred GPa, like fluids, in such a manner that the shaped charge jet penetrates layered materials in accordance with the laws of hydrodynamics, which explains the penetration force of these shaped charge jets.
Just as there are efforts to optimize the penetration force of such type shaped charge jets, there are also efforts to design suitable protection mechanisms, such as for example armor, to minimize the destructive effect of the shaped charge jet on the objects as much as possible. The further description, therefore, relates to protecting objects from the effect of shaped charge jets.
S. V. Demidkov's article “The Ways of the Shaped Charge Jets Functional Parameters Electromagnetic Control Efficiency Amplification”, 20th International Symposium on Ballistics, FL, 23-27 Sep. 2002, explains the effect of electromagnetic fields on the propagation of shaped charge jets. This article describes the state-of-the-art protection principle based on selective widening of a shaped charge jet by coupling in electric current along the propagating shaped charge jet. A capacitor-like electrode arrangement provided with two electrode plates which are spaced apart and placed before the to-be-protected object is used. FIG. 2 shows a schematic representation of such a type arrangement. The shaped charge 1 penetrates from above the electrically charged electrode plates 2 and 3, which are connected to a pulsed-current source 4 of current pulse designed as a high-voltage capacitor. At least one electrode 2 faces away from the object 5 and at least one electrode 3 faces the object 5. The at least one electrode 2 facing away from the object 5 is impacted by the shaped charge jet 1 before the at least one electrode 3 facing the object. The connections of the source 4 of a current pulse are connected to the electrode plates 2 and 3, which are penetrated by the shaped charge jet 1 in the illustrated manner. Described is that when the shaped charge jet 1 penetrates through the two electrode plates 2 and 3, an electric current developing along the jet causes the shaped charge jet 1 to disturb the jet, so that after the shaped charge jet 1 has penetrated through the electrode plate 3 facing the object, the diameter of the jet widens thereby reducing the penetration power of the jet inside the object 5. The penetration power of the jet inside the object 5 can be determined by the penetration depth of the shaped charge jet into the object.
Fundamentally an electric current can only occur along the shaped charge jet as soon as the tip of the shaped charge jet 1 hits the electrode 3 facing the object 5, producing in this manner a conducting connection between the two electrodes 2 and 3. As the shaped charge jet 1 has good electrical conductivity, a high current of several 100 kA flows between the electrode plates upon passage of the shaped charge jet through the two electrodes. However, the electric current along the jet 1 can only flow through a section of the shaped charge jet located between the electrodes as long as this section of the jet is situated between the electrode plates and has not yet exited from the rear electrode. In order to do this, the pulsed-current input 4 has to be adapted to the passage time of the shaped charge jet 1, for example in such a manner that the current flow runs in the form of a cushioned vibration and the duration of the first halfwave is attuned to the duration of the passage of the shaped charge jet. As previously mentioned, the tip of the shaped charge jet is able to propagate with a very great velocity of 7 km/s or more and thus pass the two electrode plates, which are disposed some centimeters apart, within a few microseconds. For this reason, especially the time span of coupling-in the current into the tip of the shaped charge jet is very short and consequently also the possibility of widening the cross section of the jet, as the current is only able to rise at a limited rate of change which is essentially dependent on the inductivity of the circuit.
If, as shown in example FIG. 2, plates composed of full material, for example steel, are used as the electrodes, due to the only limited thickness of the electrode plates, electric current only flows very briefly through the tip of the shaped charge jet as the electric current does not start flowing until that the tip of the jet reaches the electrode 3 facing the object 5.
However, if the tip of the jet exits immediately from the rear electrode plate 3, electrical current can no longer flow through the intermediate space between the electrodes during the whole passage period as it does through the middle region of the shaped charge jet 1. Thus there is presently no adequate way to disturb the shaped charge jet with state-of-the art means of effective protection from shaped charge jets.
DE 40 34 401 A1 describes a generic electromagnetic armor with two plates which are placed at a distance from each other and which are connected in parallel and are electrically chargeable with at least one capacitor.
WO 2004/057262 A2 describes a multiple-plate armor which has at least one plate composed of electrostrictive or magnetostrictive material.
U.S. Pat. No. 6,622,608 describes a plate armor which has at least two distance-variable plates whose distance from each other is adjustable as required by means of electromagnetic repelling forces between the plates.
Finally, DE 42 44 564 C2 describes a protective element with a sandwich-like designed structure which is provided with a coil and/or capacitor arrangement by means of which the adjacent protective plates can be accelerated to reduce the depth of penetration into the structure of an approaching shaped charged projectile.